IBs M. Oersted on the connection between 
was moved from its position ; but as his apparatus was feeble, 
and the results not strongly marked, he associated himself with 
his friend M. Esmark, Counsellor to the King, and provided a 
galvanic apparatus, consisting of twenty copper troughs, each 
of which was inches square, with a breadth of about 
inches. Each trough was furnished with two plates of copper, 
disposed so as to support the rod of copper which sustains the 
zinc plate in the fluid of the next trough. The conducting 
fluid consisted of pure water, containing /^th bf its weight of 
sulphuric acid, and as much nitric acid. The portion of each 
zinc plate immersed in the fluid is a square whose side is about 
ten inches long. A less powerful battery will be sufficient, pro- 
vided that it is able to make a metallic wire red-hot. The op- 
posite extremities of the pile are joined by a metallic wire, call- 
ed the Uniting Wire {fil conjonct^^ by Ampere and Biot,) and 
the name of the Electric Conjiict was given to the effect which 
took place in the uniting wire, and in the space around it. 
1. Above a magnetic needle, well suspended, and in equilir 
brio in the magnetic meridian, is placed a straight part of the 
uniting wire, so as to be horizontal and parallel to the needle, 
which may be done by bending it near its efficacious part. 
When this is done, the needle will be found to deviate from its 
position ; — the pole which is nearest the negative end of the bat- 
tery will move to the westward^ ‘ and if the distance of the 
needle from the uniting wire does not exceed three-fourths of 
an inch, the declination of the needle will be 45°. At greater 
distances the declination decreases proportionally ; and the dis- 
tance remaining the same, the declination varies with the 
strength of the battery. 
If the uniting wire is placed below^ instead of above, the 
needle, the effects will be inverted, and the pole which is near- 
est the negative end of the battery will move to the Eastward. 
2. lienee it follows, in general, that j/" negative electricity 
enters above the pole of the needle^ it will decline to the west, 
and if it enters below, it will decline to the East, 
If the uniting wire is made to turn in a horizontal plane, so 
as to deviate gradually from the magnetic meridian on either 
side, the declination of the needle will increase, if the wire ap^ 
proaches the needle, and will diniinish if it recedes from it, 
